3. All organic natures are progressive: that is, each individual of
them is apt to make a certain progress, under certain conditions, from
birth to maturity. But man alone has his progress in any degree in his
own hands, to make or to mar. Man alone, in the graphic phrase of
Appius Claudius, is _faber fortuna sua_, "the shaper of his own
destiny." Any other plant or animal, other than man, however miserable
a specimen of its kind it finally prove to be, has always done the
best for itself under the circumstances: it has attained the limit
fixed for it by its primitive germinal capacity, as modified by the
events of its subsequent environment. The miserable animal that howls
under your window at night, is the finest dog that could possibly have
come of his blood and breeding, nurture and education. But there is no
man now on earth that has done all for himself that he might have
done. We all fall short in many things of the perfection that is
within our reach. Man therefore needs to stir himself, and to be
energetic with a free, self-determined energy to come up to the
standard of humanity. It is only his free acts that are considered by
the moralist. Such is the definition of Moral Science, that it deals
with _human acts_; acts, that is, whereof man is master to do or not
to do. (c. i., nn. 1, 2.)

4. We have it, then, that a morally good act is an act that makes
towards the progress of human nature in him who does it, and which is
freely done. Similarly, a morally evil act is a bar to progress, or a
diversion of it from the right line, being also a free act. Now, that
act only can make for the progress of human nature, which befits and
suits human nature, and suits it in its best and most distinctive
characteristic. What is best in man, what characterises and makes man,
what the old schoolmen called the _form_ of man, is his reason. To be